NASA announced that the assembly of the James Webb Space Telescope is now complete and ready to move into the testing phase. Some of the testing of the individual components, such as the Integrated Science Instrument Module (ISIM) have been cyro-tested at the Goddard Space Flight Center in Greenbelt Maryland, but now it's time to test the entire telescope assembly, including the primary mirror segments, the science instruments and the power busses.
The next phase of the JWST Mission is to start one of the most rigorous testing programs ever undertaken for a space telescope. Given that there will be no ability to repair anything if it goes wrong after launch, scientists and engineers have to get this right the first time.
Later this year, at the Johnson Spaceflight Center, an old friend has been refurbished to help with the testing: Chamber A. It was originally built in the 1960's for use during the Apollo space program, it was rebuilt and modified over a course of three years to make it suitable for testing for the JWST mission.
This vacuum chamber is big enough to house the entire telescope and they are going to cool the chamber down to JWST's operating temperature of 34 Kelvin, then shake it, open it, close it, subject it to loud sounds to simulate a rocket launch.
But most importantly, they are going to FOCUS IT! Something that would have been nice to do with the Hubble Space Telescope before it launched in 1990. Oh well, lessons learned.
NASA Johnson's Chamber A is the largest vacuum chamber in the world. It is 55 feet (16.8 meters) in diameter by 90 feet (27.4 meters) tall. The door weighs 40 tons and is opened and closed hydraulically.
It took three years for NASA Johnson engineers to build and remodel the chamber interior for the temperature needed to test the Webb Some of the things they've done is upgraded the helium system, our liquid nitrogen system, and air flow management. Temperatures in Chamber A can now drop farther than ever -- down to -439.9 Fahrenheit (-262.1 Celsius or 11 degrees Kelvin) which is 11 degrees above absolute zero. When full of air, the air in the chamber weighs 25 tons, about 12 1/2 Volkswagen Beetles; when all the air is removed the mass left inside will be the equivalent of half of a staple.
Which I think is a weird way to put it, but there you go...